Questions and Answers
Who was the first to observe cell walls?
Antoni van Leeuwenhoek visualized living cells for the first time.
True
What component of cells did Robert Brown conclude is fundamental?
nucleus
The Modern Cell Theory states that every living organism is made up of one or more ____.
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Which of the following is NOT part of the Modern Cell Theory?
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What is the function of ribosomes?
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What distinguishes smooth ER from rough ER?
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The ____ apparatus modifies and stores proteins before sending them to other destinations.
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What role do lysosomes play in a cell?
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Vacuoles are part of the endomembrane system in cells.
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What is contained in the central vacuoles of mature plant cells?
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Study Notes
Discovery of Cells
- Robert Hooke first observed cells in 1665 using a microscope on oak tree bark, identifying cell walls in dead cells.
- Antoni van Leeuwenhoek visualized living cells in 1674 with finely crafted lenses, coining the term "animalcules."
- Robert Brown discovered the nucleus as a key cell component in 1831.
- Matthias Schleiden established in 1838 that all plant parts are made of cells.
- Theodore Schwann confirmed in 1839 that cells are the fundamental unit of animal tissues.
- Rudolf Virchow proposed in 1858 that all cells arise from pre-existing cells.
Modern Cell Theory
- Every living organism comprises one or more cells.
- The smallest living organisms are single-celled, while multicellular organisms are composed of various cell types.
- All cells arise from pre-existing cells and share a common descent.
- Cells have evolved and modified over time but maintain fundamental similarities.
Cell Structure
The Nucleus
- Contains most of the cell's genetic material and is among the most visible organelles.
- Enclosed by a nuclear envelope with a double membrane composed of lipid bilayers.
- Houses the nucleolus, the site for ribosome synthesis.
Ribosomes
- Complexes made of ribosomal RNAs and proteins responsible for protein synthesis.
- Essential for cell growth and reproduction of cellular components.
Endoplasmic Reticulum (ER)
- Extensive membrane network, accounting for more than half of the membranes in many eukaryotic cells.
- Divided into:
- Smooth ER: Lacks ribosomes; functions include lipid synthesis, carbohydrate metabolism, drug detoxification, and calcium ion storage.
- Rough ER: Studded with ribosomes; involved in synthesizing secretory proteins and membrane production.
Golgi Apparatus
- Composed of flattened membranous sacs (cisternae) functioning in processing, modifying, and storing proteins from the ER, directing them to various destinations.
Lysosomes
- Membranous sacs containing hydrolytic enzymes that digest macromolecules.
- Play a crucial role in recycling cellular components and processing nutrients.
Vacuoles
- Large vesicles arising from the ER and Golgi apparatus, integral to the endomembrane system.
- Functionality includes:
- Central Vacuoles: Present in mature plants, filled with cell sap storing inorganic ions and assisting in cell growth through water absorption.
- Contractile Vacuoles: Found in unicellular eukaryotes, function to expel excess water, maintaining osmotic balance.
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Description
Explore the pivotal discoveries that led to the formulation of the modern cell theory. This quiz covers key figures such as Robert Hooke and Antoni van Leeuwenhoek, highlighting their contributions to cell biology. Test your knowledge on the historical advancements that shaped our understanding of cells.
